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BUG#15935: In mysql_update, don't use full index scan when we could have used quick select scan.

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mysql-test/r/update.result:
  Testcase for BUG#15935
mysql-test/t/update.test:
  Testcase for BUG#15935
sql/sql_update.cc:
  BUG#15935: 
  - Do account for the fact that used_index!=MAX_KEY is also true for cases
    when quick select is used, and use quick select then (and not full index scan).
  - Also removed the redundant "used_index= MAX_KEY" statement
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unknown
2006-01-25 23:25:23 +03:00
parent 52ff597a8a
commit d33ac37ba6
3 changed files with 28 additions and 2 deletions
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15
mysql-test/r/update.result
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@ -358,3 +358,18 @@ update t2,t1 set f1=3,f2=3 where f1=f2 and f1=1;
affected rows: 3
info: Rows matched: 3 Changed: 3 Warnings: 0
drop table t1,t2;
create table t1 (a int);
insert into t1 values (0),(1),(2),(3),(4),(5),(6),(7),(8),(9);
create table t2 (a int, filler1 char(200), filler2 char(200), key(a));
insert into t2 select A.a + 10*B.a, 'filler','filler' from t1 A, t1 B;
flush status;
update t2 set a=3 where a=2;
show status like 'handler_read%';
Variable_name Value
Handler_read_first 0
Handler_read_key 1
Handler_read_next 1
Handler_read_prev 0
Handler_read_rnd 1
Handler_read_rnd_next 0
drop table t1, t2;